A channel through which cooling water flows is formed in a cylinder head of an internal combustion engine. Japanese Patent Laid-Open No. 2013-133746 discloses a configuration in which, in order to cool air inside an intake port, a first cooling water circuit through which cooling water that cools the periphery of an intake port circulates is provided inside a cylinder head independently from a second cooling water circuit through which cooling water that cools the periphery of an exhaust port circulates that is provided inside a cylinder block and the cylinder head.
The first cooling water circuit includes an intake-port cooling water passage that is formed in the cylinder head. The intake-port cooling water passage is connected to a cooling water introduction portion that is provided in an end face in a width direction of the cylinder head. The intake-port cooling water passage widens on the lower side of an intake port from the cooling water introduction portion, and extends to the upper side of the intake port through a side face of the intake port, and is connected to a cooling water lead-out portion that is provided in an end face in a longitudinal direction of the cylinder head through the upper side of the intake port.